Integral leak testing measures the total leak rate of a component or system to verify it meets functional tightness requirements. Unlike local leak testing, which pinpoints the leak location, integral testing focuses on overall performance and tightness under real-world conditions.

It is commonly used in:

Bubble testing and integral leak testing are both non-destructive methods, but they differ significantly in precision, automation, and suitability for industrial applications.

Bubble testing may still be used for simple visual checks or prototypes, but integral leak testing is the method of choice in modern production for its reliability, automation potential, and quantifiable results.

Choosing the right leak detection method depends on several factors – from the purpose of the test to the component’s real-life operating conditions. The pressure inside the test specimen plays a crucial role in determining which method to use.

Key questions to ask:

No system is 100% tight. Leak testing should confirm the required functional tightness – preventing ingress or egress of fluids, gases, or contamination under real conditions.

Need help defining your leak rate or test setup? Talk to our experts or explore our leak testing services.

Overpressure leak testing involves pressurizing a component with a gas (often air or nitrogen) to a level above atmospheric pressure. The component is then monitored for any loss of pressure or escape of gas, which would indicate a leak. This method is particularly suitable for components that are designed to operate under positive pressure, such as systems like pipelines, valves, and pressure vessels.

Vacuum leak testing, on the other hand, involves evacuating air from the component or system to create a vacuum environment. Leaks are detected by observing how quickly the vacuum degrades or by introducing a tracer gas (commonly helium) and using a helium mass spectrometer to detect any gas escaping into the vacuum chamber.

Vacuum testing offers higher sensitivity, often capable of detecting extremely small leaks (down to 10⁻⁹ mbar·l/s or lower), which makes it ideal for components designed to operate under vacuum or when ultra-sensitive leak detection is required.

Tracer gases like helium enhance both overpressure and vacuum testing by increasing detection sensitivity. In overpressure methods, helium can be used and detected by a sniffer probe. In vacuum methods, helium introduced outside the sealed component will be drawn in through leaks and detected by the spectrometer.

Envelope testing is a specific form of integral leak testing. It involves placing the test object in a sealed chamber (the “envelope”) and introducing a tracer gas under vacuum or pressure. If there is a leak, the gas enters or escapes the object and is detected by a connected leak detector.

Benefits of envelope testing:

Leak detection setups are not one-size-fits-all. At Pfeiffer, we offer three scalable solutions – all built with our own vacuum technology and components:

Vacuum leak testing is often favored over atmospheric pressure methods because tracer gases move faster in vacuum.

This leads to:

We offer a full range of leak detection technologies – from tracer gas systems to air-based testers – to meet diverse requirements in sensitivity, speed, and integration.

1. Tracer gas leak detectors (helium/hydrogen)
Used for high-sensitivity, quantifiable leak testing in safety-critical applications.

The right tools can make helium leak detection more precise and efficient.

Key accessories include:

Efficient and precise leak testing depends on a reliable vacuum setup. Pfeiffer Vacuum+Fab Solutions provides a full portfolio of vacuum pumps and accessories that support both stand-alone detectors and integrated systems.

Vacuum pumps

Accessories for test accuracy and control

Speeding up leak testing and maintaining sensitivity requires a well-tuned system. The choice between partial-flow and full-flow setups plays a key role.

System design tips for faster leak testing

Full flow vs. partial flow: What to use when

Full flow routes all tracer gases through the detector – ideal for sensitivity.
Partial flow splits the gas stream – ideal for speed and scalability.

With over 60 years of experience in leak detection and decades of expertise in vacuum technology, Pfeiffer is your trusted partner for complete leak testing solutions. Our portfolio includes tracer gas and air-based leak detectors, high-performance vacuum pumps, and all essential components such as chambers, valves, and gauges.

Beyond hardware, our global service network and application laboratories offer comprehensive leak testing services, including feasibility studies, system optimization, and on-site support. We help you select the most efficient methods, define suitable leak rates, and tailor your system setup – ensuring reliable performance wherever your production is located.